In recent years, color reproduction accuracy is considered as one of important matters to maintain the quality of printed matters. The color reproduction accuracy is evaluated by using a color difference (for example, AE) between color values (for example, L*a*b* values) and colors defined according to standards in the printing industry (such as FOGRA in Europe, GRACoL in US, and Japan Color in Japan), and such standards each defines a tolerance of the color difference. To achieve an allowable color reproduction accuracy, color conversion is generally performed by using ICC (International Color Consortium) profiles including a target profile and a printer profile.